Reviving old skills

1 February 2005



Richard Neale presents three examples of how traditional laundering skills can provide a reassuring difference in quality for the modern workwear sector


Quality rather than price is now becoming the driving factor in the workwear sector. That is not to say that the customer is prepared to pay a higher price for quality; prices have simply been driven down to a point where quality starts to come into the picture.

The only way to make a margin with this type of customer is to be able to deliver a discernible difference in quality without it costing any more. This calls for old-fashioned laundering skills which have been all but forgotten in many laundries.



Bio-decontamination

In the last few years, greater effort appears to have gone into the bio-decontamination of food industry workwear than into healthcare linen. Food handlers are now expected to work under controlled conditions with regular changes of garment, whereas healthcare staff still take their uniforms home to be laundered in the family wash.

The market leaders in the rental sector are now checking the surface of their laundered garments for surviving micro-organisms and making their routine test results available to their customers as part of the customer’s quality assurance regime. Most launderers use simple dipslides for monitoring because these are relatively inexpensive and can be monitored in-house.

There are now three types of slide in regular use. The first and most popular monitors Total Viable Count (TVC) to give an indication of the total of every type of surviving micro-organism on the cloth surface. Any surviving bugs grow to form scarlet colonies on the slide surface. Some customers regard yeasts, fungi and moulds as hazardous and there is a specific dipslide for these.

It is possible to identify different species from their colours but that is pushing the accuracy of the dipslide method, which is only really designed to signal a warning to the launderer. The most recent slide to be introduced is specific to coliforms and other bacteria from the gut, such as E.coli.

Until recently the standard technique for achieving a total bug kill relied on implied thermal disinfection in the wash process. The UK Department of Health recognises only those wash processes which include a stage in which the wash liquor is held at a temperature of 71C for at least three minutes, plus mixing time.

Chemical disinfection has not yet been recognised in the UK because of the risk of encouraging mutation and the creation of more resistant species such as MRSA (Methicillin-Resistant Staphylococcus Aureous) and VRSA (Vancomycin-Resistant Staphylococcus Aureous).

Leading rental operators are starting to use anti-microbial fabrics that effectively inhibit the growth of any micro-organism on the cloth surface. The market is moving and fresh opportunities are being created as customers demand hygienic cleanliness and regular proof of this.



Crease removal

Poor crease removal is no longer acceptable because it is possible to produce polyester cotton garments that are substantially crease-free by application of sound laundering techniques and good supervision, without increasing the production cost by much, if anything.

The secret lies in recognising the different types of creasing and identifying the stage at which they are being introduced and how to prevent them. It is virtually impossible to produce polyester cottons which are free of long “roping” creases unless the work is processed in a well designed washer-extractor with good lifters and correct rotational speed.

The lifter must be large enough to get hold of the work and the G force in the wash must hold the garments against the side of the cage until the 10.30 or 11 o’clock position, from where they fall cleanly across the cage diameter into the lower liquor.

If the work rolls off the lifter at the 9 o’clock position, long roping creases are introduced, especially in the hot wash. Overloading the cage causes pressure creases in the hot wash when those garments at the bottom become crushed, which is why the maximum cage loading is about 80% of the stated design load for cotton goods.

Orange peel wrinkling is difficult to avoid and is common with brand new fabric. It is minimised by good weaving (to produce even cloth tensions) and perfect relaxation after finishing.

Inferior quality cloth can be recognised by this effect and cheaply produced garments made to a price often also display seam pucker after a few washes. The laundering process has finished the relaxation and the puckering is a natural consequence of this.
Tight, cracked ice creasing is caused by thermal shock between the hot wash and the first rinse. Polyester cotton has to be brought down slowly in temperature until it is below 52C to avoid the crow’s foot wrinkling in which the entire fabric takes on the appearance of cracked ice. The maximum rate of cooldown is 4C per minute and sensitive fabrics can only be cooled at half this rate.

Finally there are the pressure creases put in during normal wear. Seat creases set in at the supermarket checkout must be taken out by raising the temperature in the wash, usually to over 75C. There is no point in relying on the tunnel finisher because it is not designed to remove this type of creasing.



Removing stains

Traditional launderers who attended the old six month courses that used to be run by the former British Launderers Research Association would have little or no problem in removing the wide variety of stains and soiling with which modern workwear becomes contaminated.

They would be horrified at the ease with which the modern launderer reaches for the telephone to summon the detergent supplier and even more appalled at the most common solution which is to increase the bleach.

Traditional launderers were taught to soften protein staining (caused by blood, sweat, fish slime and meat juices) by using a low temperature first wash below 38C, before a main wash at high temperature with plenty of mechanical action and good alkalinity. Frequently an emulsifier in the first wash helps to break up the fatty proteins so that they disperse into the wash liquor before the end of the main wash.

They can then be held in the wash liquor by an effective suspending agent so that they cannot re-deposit onto the fabric and cause greying.

A good emulsifier will also improve the removal of oil-based staining and give a result which is even better than drycleaning, despite the fact that drycleaning fluid has a far greater removal power for oil than water does.

Finally, a good professional launderer will allow a small dosage of oxidising agent (bleach) for decolouring vegetable dye staining from tea, coffee and red wine and other natural dyes.

If protein staining has been effectively washed out, then only a small amount of bleach is needed and chemical damage to the cotton component is effectively minimised.
It is possible to measure numerically the power of a wash process for removing each type of staining. The Swiss organisation EMPA manufactures standard calibrated test fabric which changes colour by a visible and measurable amount depending on the effectiveness of the process. The performance is measured using a standard laundry reflectometer.

Many laundries have one of these and use it regularly for measuring whiteness without realising that it can also be used for monitoring soil and stain removal power.
This can be a very powerful and objective technique for comparing competing detergent systems.





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